Process for melting and refining of nonferrous metals



Pled Dec. 7, 1923 Patented Get. 13, 1925.

UNITED STATES y 1,556,591- PATENT oFFlcE.

DANIEL CUSHING, OF LOWELL, MASSACHUSETTS, ASSGN'OR T0 THE BARRETT COM-PANY, A CORPORATION 0F NEW JERSEY.

PROCESS FOR MELTING AND REFINING OF NOTTERROUS METALS.

Application med December 7, 192s.- seriai No. 679,111?.

To all 'whom t may concern:

Be it known that DANIEL CUSHING, a cltizen of the United States,residing at Lowell, in the county of Middlesex and State ofMassachusetts, has invented certain new and useful Improvements inProcesses for Melting and Refining of Nonfferrous Metals, of which thefollowing is a specification.

Heretofore the melting of non-ferrous metals and their alloys has beenaccomplished in a variety of ways either for the purpose o'f purifyingthem or modifying their characteristics or treating them with othersubstances or merely for the purpose -of getting them into a liquidstate so that Ithey could be poured into molds or cast intov ingots.

One of the most common methods of melting such metals or their alloys isto introduce them into Crucible furnaces that are heated from theoutside by using gas, oil, coal, coke or other` fuels. Objections anddifficulties often arise because the c rucibles are expensive and differin characteristics;

the heat from the fuel must betransferred Cil to the fact that eachcrucible is necessarily of comparatively small size a large number oisrequired where large castings are needed. i When reverberatory furnaces.are used for melting metals t y it would be if 'he material to hemelted were in 'direct contact with incandescent fuel, and it isdifficult to control the operations which require skilled operators andcareful manipulation and in these furnaces the flexibility as to tonnagecast is limited. Electric furnaces are also sometimes used for thispurpose but entail large cost for power and .great expense forlnstallation and repair. It has been known for a long time that cupolafurnaces afford the cheapest means of melting iron because of the directcontact between the metal and fuel with a corresponding maximumabsorption of heat. At the same time such'units can, be built andoperated in various sizes, areeasily-con-y trolled and the same furnacecan be charged with charges of different s izes'at different times.While cupolas are commonly use d for melting iron they have not provensat e fuel cost is higher thanA presence of slagfrom the necessaryfluxingl of the ash in ordinary fuels is very objectionable in mostnon-ferrous metals; fuels differ from each other and even differentbatches or fuel from the same source are suciently difl'erentfrom eachother as to cause difliculty and require constant exercise of diligencein order to obtain an approximately correct and proper control of thegases and of the slag; and some non-ferrous metals, such as .thosecontaining zinc for example, suffer great losses from volatiliza# tionin the ordinary cupola furnaces.

By the present invention difficulties and objections have been overcomeand non-ferrous metals have been readily and satisfactorily melted in acupola furnace in a` rapid i and efficient manner without great loss ofmaterial.

lOne of the features that has contributed to the successful developmentof my invention is the selection of the right sort of fuel or a fuelhaving the proper characteristics for melting non-ferrous metals ortheir alloys in a cupola furnace. l have found that a fuel will operatesatisfactorily for this purpose if it has sufficient mechanical strengthor resistance to crushing `to enable it to support a cupola chargeprovided it is at the same time substantially free from sulfur and ashand other deleterious materials and also possesses sufficient thermalcapacit or so many B. t. u. per pound toenable it to develop therequisite amount of heat without necessitating such a strong air blastthat an excessive oxidizing atmosphere is resent inthe furnace., Anexample of suc a fuel is the coke obtained from coking 'coal tar pitchin a .bee hive oven. This coke is mechanically strong, consists of about,98% to 99% or' fixed. carbon, is substantially `ars Masamireverberatory urnace;fthe melting and re fining can be accomplished in ashorter period of time than with other types of furnaces; the gasesescape up thestack instead of escaping into the plant as is often thecase inv non-ferrous foundries and smelting works; the lcoke to be usedby this process can be obtained of substantially uniform quality thuseliminating uncertainties in the results; the shape and size of themetal to The lowv blast enables line material such as borings andturnings or other similar fine materials to be melted, while the largesizes are limited only by the size of the charging door; and a verysmall amount of slag is' produced from ash ir the fuel as there issubstantially nol ash in the coke.

I claim:

1. The process. which comprses melting a non-ferrous metal While 1ndirect contact with incandescent pitch coke which is substantially freefrom ash and ,materials that would have a deleterious effect upon saidmetal.

2. The process which comprises melting a non-ferrous metal while indirect contact with incandescent coke which is substantially free fromash and materials that i would have a deleterious effect upon said metaland possesses high compressive strength. y

3. The process which comprises melting a non-ferrous metal while indirect contact with incandescent coke` which is substanwould have adeleterious effect upon said metal and containing at least 98% of fixedcarbon.

, 4. The process which comprises melting a non-ferrous metal While indirect contact with incandescent pitch coke which is substantially freefrom ash and materials that Would have a deleterious effect upon saidmetal andi having a thermal value of about 14,500 B. t, u. per pound.

5. The process which comprises meltingj a non-ferrous metal While indirect contact with incandescent coken which is substantially free fromlash andV materials that would have a deleterious effect upon said metal,the access of air being restricted to preven't an excessive'oxidizingatmosphere.

6. The process which comprises melting a. non-ferrous metal whilesupported by incandescent coke which is substantially free from ash andmaterials that/'Would .have a deleterious effect u'pon said metal.

7. The process which comprises melting a non-ferrous metal While indirect contact with. incandescent coke which is substantially free fromash and materials that would have a deleterious effect upon said metal,the air blast being maintained below 4 ozs. of pressure for 18 dia'.furnace.

8. The process Which comprises refining impure copper by melting itincontact with pitch coke, which is substantially free from and materialsthat would have a deleterious effect upon said co per,and possesses highcompressive strengt 9. The process which comprises melting' impurecopper while in direct contact with incandescent pitch coke,. which issubstantially free from and materials that would have a deleteriouseffect upon said copper, the access of air being restricted to provide areducing atmosphere.

In testimony whereof I afiix my signature.

DANIEL CUSHING.

